Fez1/Lzts1 alterations in gastric carcinoma

Purpose: Loss of heterozygosity (LOH) involving the short arm of chromosome 8 (8p) is a common feature of the malignant progression of human tumors, including gastric cancer, We have cloned and mapped a candidate tumor suppressor gene, FEZ1/LZTS1, to 8p22, Here we have analyzed whether FEZ1/LZTS1 alterations play a role in the development and progression of gastric carcinoma. Experimental Design: We examined Fez1/LZTS1 expression in 8 gastric carcinoma cell lines by Western blot, and in 88 primary gastric carcinomas by immunohistochemistry. Twenty-six of these 88 primary gastric carcinomas were also microdissected and tested for LOH at the FEZ1/LZTS1 locus and for mutation of the FEZI/LZTSI gene. Furthermore, we studied the FEZ1/LZTS1 gene regulation and transcriptional control and the methylation status of the 5' region of the gem in ah 8 gastric carcinoma cell lines. Results: Fez1/Lzts1 protein was barely detectable in all of the gastric cancer cell lines tested and was absent or significantly reduced in 39 of the 88 (44.3%) gastric tarcinomas analyzed by immunohistochemistry,,vith a significant correlation (P < 0.001) to diffuse histotype, DNA allelotyping analysis showed allelic loss in 3 of 17 (18%) and microsatellite instability in 4 of 17 (23.5%) cases informative for D8S261 at the FEZ1/LZTS1 locus. When we compared the presence of LOH with Fez1/Lzts1 expression, we found loss of protein expression in all three of the tumors with allelic imbalance at D8S261, A missense mutation was detected in one case that did not express Fez1/Lzts1, Hypermethylation of the CpG island flanking the Fez1/Lzts1 promoter was evident in six of the eight tell lines examined as well as in the normal control. Conclusions: Our findings support FEZI/LZTSI as a candidate tumor suppressor gene at gp in a subtype of gastric cancer and suggest that its inactivation is attributable to several factors including genomic deletion and methylation.

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